Many medical experts agree that stress is an important factor in disease prevention and recovery. Measuring vital body signs to calculate a measure of user stress is known, for example a way to measure the stress-level of a car driver, including a camera/observer recording the road condition, is described in “Quantifying driver stress: developing a system for collecting and processing bio-metric signals in natural situations,” by Healey J, Seger J, Picard R., in: Biomed. Sci. Instrum. 1999; 35:193-8, referred to hereinafter as “Healey”. It is also known that national and other legislation place boundaries on noise-levels and other external signals/influences to workers.
In U.S. Pat. No. 6,607,484, a behavior and stress management recognition apparatus is disclosed. It comprises a reference sensor information corpus storing records of environment (season, time, place, posture, action, behavior, and expected behavior), physical information (pulse rate, body temperature, galvanic skin reflex (GSR), and voice pitch), degree of stress, and dialogue structure. It further comprises storing subjective (stress) data for persons in the address book of personal information management (PIM) software. It further mentions an ultrasonic distance sensor for determining if a person enters someone's personal space, an odor sensor for determining a bad smell or strong smell, and determining the degree of stress from task data and schedule.
The existing system is relatively complex and requires a lot of user interaction to learn the stressfulness of any particular situation, which makes the stress measurement relatively subjective. It only takes into account a limited number of aspects of relevant environmental circumstances that may be stress inducing. The cited systems do not provide accurate information about the stressors in an environment of a person.